Diesel trucks are major contributors of nitrogen oxides (NO) andprimary particulate matter smaller than 2.5 μm (PM) in thetransportation sector. However, there are more obstacles to existingestimations of diesel-truck emissions compared with those of cars. Theobstacles include both inappropriate methodology and missing basic data inChina. According to our research, a large number of trucks are conductinglong-distance intercity or interprovincial transportation. Thus, the methodused by most existing inventories, based on local registration number, isinappropriate. A road emission intensity-based (REIB) approach is introducedin this research instead of registration-population-based approach. Toprovide efficient data for the REIB approach, 1060 questionnaire responsesand approximately 1.7 million valid seconds of onboard GPS monitoring datawere collected in China.The estimated NO and PM emissions from diesel freighttrucks in China were 5.0 (4.8–7.2) million tonnes and 0.20 (0.17–0.22)million tonnes, respectively, in 2011. The province-based emission inventory isalso established using the REIB approach. It was found that the drivingconditions on different types of road have significant impacts on theemission levels of freight trucks. The largest differences among the emissionfactors (in g km) on different roads exceed 70 and 50% forNO and PM, respectively. A region with more intercity freewaysor national roads tends to have more NO emissions, while urbanstreets play a more important role in primary PM emissions fromfreight trucks. Compared with the inventory of the Ministry of Environment Protection, whichallocates emissions according to local truck registration number and neglectsinterregional long-distance transport trips, the differences forNO and PM are +28 and −57%,respectively. The REIB approach matches better with traffic statistical dataon a provincial level. Furthermore, the different driving conditions on thedifferent roads types are no longer overlooked with this approach.
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